02254nas a2200253   4500008004100000022001400041245010200055210006900157260007100226300001400297490000700311520133300318100002901651700002301680700002301703700001801726700002001744700002301764700001601787700002401803700001801827700002701845856012801872       2008                        eng d  a0897-475600aChemical inhomogeneity and mixed-state ferromagnetism in diluted magnetic semiconductor Co : TiO20 aChemical inhomogeneity and mixedstate ferromagnetism in diluted   a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcFEB  a1344-13520 v203 a<p>Diluted magnetic semiconductors (DMS) are among the most intensely investigated materials in recent times in view of their great application potential. Yet, they are also the most controversial because of the possibility of extrinsic effects attributable to dopant solubility and clustering, point defects, incorporation of unintentional impurities, etc. This has highlighted the central role of materials chemistry in rendering a specific microstate and property response. In this work, we provide a combined window of high-resolution scanning transmission electron microscopy and electron energy-loss spectrometry, X-ray absorption (XAS)/X-ray magnetic circular dichroism (XMCD), and magnetization measurements on epitaxial rutile CoxTi1-xO2 (x = 0-0.06) system (the first discovered oxide-DMS, which continues to be controversial) grown at low temperature (400 degrees C) under different ambient atmospheres. The study brings out a mixed-state scenario of ferromagnetism involving intrinsic DMS (uniform dopant distribution at low dopant concentration) and coupled cluster magnetism, involving cobalt associations within the matrix at higher concentrations. We also show that by matrix valence control during growth, it is possible to realize a uniform embedded cluster state and the related coupled cluster magnetism.</p>1 aOgale, Satishchandra, B.1 aKundaliya, Darshan1 aMehraeen, Shareghe1 aFu, Lian-feng1 aZhang, Shixiong1 aLussier, Alexandre1 aDvorak, Joe1 aBrowning, Nigel, D.1 aIdzerda, Yves1 aVenkatesan, Thirumalai  uhttp://library.ncl.res.in/content/chemical-inhomogeneity-and-mixed-state-ferromagnetism-diluted-magnetic-semiconductor-co-002726nas a2200253   4500008004100000022001400041245013800055210006900193260007100262300001200333490000700345520177100352100002502123700001902148700002202167700002602189700001802215700001902233700002402252700002302276700001802299700002902317856012602346       2008                        eng d  a0897-475600aCo : CdS diluted magnetic semiconductor nanoparticles: radiation synthesis, dopant-defect complex formation, and unexpected magnetism0 aCo CdS diluted magnetic semiconductor nanoparticles radiation sy  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJAN  a440-4460 v203 a<p>Incorporating a dopant into a nanoparticle is a nontrivial proposition in view of the size dependent surface versus bulk energy considerations and the intrinsic proximity of the surface to the interior, which facilitates migration to the surface. If realized and controlled, however, it can open up new avenues to novel nanomaterials. Some previous studies have shown the dopability of nanosystems but only with specific surface functionalization. Here, we demonstrate the successful dopant incorporation via a new route of pulsed high energy electron induced synthesis. We choose a system Co:CdS (dilutely cobalt doped cadmium sulfide) in view of the well-known application-worthy properties of CdS and the potential possibility of its conversion to a diluted magnetic semiconductor of interest to spintronics. By using various techniques, we show that matrix incorporation and uniform distribution of cobalt are realized in US nanocrystals without the need for additional chemical or physical manipulation. Optical and photoluminescence properties also support dopant incorporation. Interestingly, although magnetism is realized, it is weak, and it decreases at higher cobalt concentration. First principle density functional calculations are performed to understand this counterintuitive behavior. These calculations suggest that the introduction of parent cation or anion vacancies lead to magnetic moment reduction, albeit marginally. However, with some Co impurity fraction in the octahedral interstitial site inside the wurtzite cage, the magnetic moment drops down drastically. This study reveals that defect states may have an interesting role in dopant stabilization in nanosystems, with interesting system dependent consequences for the properties.</p>1 aBogle, Kashinath, A.1 aGhosh, Saurabh1 aDhole, Sanjay, D.1 aBhoraskar, Vasant, N.1 aFu, Lian-feng1 aChi, Miao-Fang1 aBrowning, Nigel, D.1 aKundaliya, Darshan1 aDas, Gour, P.1 aOgale, Satishchandra, B.  uhttp://library.ncl.res.in/content/co-cds-diluted-magnetic-semiconductor-nanoparticles-radiation-synthesis-dopant-defect-0